1. Field of the Invention
This invention relates generally to a pavement marker for engagement with an underlying roadway surface and more specifically to a pavement marker that uses a curved solid glass member with reflective material attached thereto as a retroreflective lens.
2. Description of the Prior Act
There have been many road markers suggested and patented. Road markers come in all different shapes and some use coloring to indicate a specific direction. For example, some road markers reflect white if a vehicle is going in the right direction and reflect red if the vehicle is going in the wrong direction against traffic. Roadway lane markers indicate a traffic lane for a driver at night time and are more desirable than painted lines, especially in fog or rain, and they are exceptionally helpful in the light glare of oncoming vehicles.
U.S. Pat. No. 3,332,327 discloses a pavement marker having a lens of synthetic resin in which the front face is inclined at a predetermined angle. U.S. Pat. No. 4,232,979 and U.S. Pat. No. 4,340,319 improve on U.S. Pat. No. 3,332,327 in that a thin layer of glass is applied over the synthetic resin to improve the abrasion resistant properties. U.S. Pat. No. 4,930,870 uses a transparent plastic material and various reflecting means. U.S. Pat. No. 4,717,281 uses a circular body with lens elements made from a polycarbonate. The lens in U.S. Pat. No. 4,717,281 is at a constant angle to the roadway surface but is curved in a circular configuration. U.S. Pat. No. 4,653,959 is a circular roadway marker that reflects light in a 360 degree pattern and also uses a reflective tape around the edge of the circular marker.
All of the above have one common fault, and that is low abrasion resistance of synthetic resin. U.S. Pat. No. 4,232,979 and U.S. Pat. No. 4,340,319 attempt to improve the abrasion resistance by placing a thin layer of glass over the synthetic resin, however, this thin layer tends to break and sharer and the synthetic resin therefore has no protection.
What is needed is a road marker that has high abrasion resistance and will not break and shatter with use.